poj 2082 Terrible Sets(单调栈)

#include<cstdio>#define MAX_N 50050#define MAX(x,y) ((x)>(y)?(x):(y))using namespace std;int stack[MAX_N],l[MAX_N],r[MAX_N],d[MAX_N],w[MAX_N];int n;int cal(){int tot=0;for(int i=0;i<n;i++){while(tot>0&&d[stack[tot-1]]>=d[i])tot--;l[i]=tot==0?0:(stack[tot-1]+1);stack[tot++]=i;}tot=0;for(int i=n-1;i>=0;i--){while(tot>0&&d[stack[tot-1]]>=d[i])tot--;r[i]=tot==0?n:stack[tot-1];stack[tot++]=i;}long long res=0;for(int i=0;i<n;i++)res=MAX(res,d[i]*(w[r[i]]-w[l[i]]));return res;}int main(){while(~scanf("%d",&n)&&(n!=-1)){int temp;w[0]=0;for(int i=0;i<n;i++){scanf("%d%d",&temp,&d[i]);w[i+1]=w[i]+temp; }printf("%d\n",cal());}}